Attention Dual Battery Owners!

[Dr Jan Itor]

I've been collecting parts for a dual battery system and am almost ready to do the install.

Question - what brand/model do you use for your second battery? Until I install the tray I won't be sure of what size will fit, so I'm just looking for an idea of what everyone else uses.

[Dave]

I have a 105Ah Marine battery, quite a large one and fits fine. What tray have you got?

[Waz]

G'day. It might pay to do a bit of research and select a battery based on what you intend to use it for. Some people use a deep cycle because it 's better suited to running a fridge and only as a cranking battery only if the main one is flat. Lot's of conjecture on this one though.

[Dr Jan Itor]

Dave - I have the TJM tray. It was a toss-up between them and ARB, and it came down to TJM being just around the corner.

Waz - I was thinking deep cycle. I'll be running the usual items like a fridge and some lights to start with.

[Rich]

You shouldn't be running your fridge or anything else from your second battery, 2'nd Battery should be isolated and everything should run from the main battery. That way there is no potential to end up with 2 flat batteries.

IE if you are winching and stall your engine and the main battery is flat from winching, your auxillary may not start you if you have been running the fridge from it. OR if you are running things from your second battery and your power starts to drop, the relay will not isolate the batteries until power has also drained from your main battery down to a certain level - could be too late!

Don't forget when the main battery is fully charged, both batteries are connected in parallel, so if you are running a fridge from your second battery, you are really running it from both until both drop below a certain level of charge.

Most people use a cranking battery as their Auxillary as well, but depends what you are intending to do with it, horses for courses.

Mine main Battery (like most) is isolated whenever the main battery voltage drops below about 11.8 Volts(?)and I can manually over ride it if I need to jump start from the second Batt. In this system, the main Batt always is also the first to charge. That way I always have a fully charged second battery that I know is going to be there if I need it.
So in Summary, if I run everything I want from my main battery and flatten it, I manually jump start from my auxillary which was isolated and remains fully charged, and then when I drive (manual over ride now removed) the main battery charges first alone in isolation and when it's charge reaches a good level, the relay automatically switched both back in parrellel and charges both.
A cranking battery will be buggered if the charge drops to about half. A deep cycle battery will not handle winching very well or constant cranking.
My 5 cents, since 2 cents are obselete!
Hope this helps.

[TOMUCH]

Rich, sorry mate I will have to disagree with you on this point... my opinion and that of many others is to, run everything that is considered AUX from your second battery... and yes it needs to be isolated form your cranking battery.. Of course this all depends on the configuration of your setup.. most normal isolators (Piranaha and the like) will not handle cranking amps running through them... so I keep a small jumper lead in my car just long enough to get from the + AUX to + Main.. since botha batteries are earthed together... howeer this should never be needed unless you leave your lights on or something and drain your start battery... your isolator will protect your cranking battery from being drained because once charging voltage is reduced to 12.4 V (engine off) the batteries are isolated from each other...

As for the AUX battery if you are not intending to crank from it all the time, then a deep cycle battery is the way to go.. it will run your fridges longer and recover faster than a cranking battery.. .if you intend on occassional cranking or winching from your AUX then I would suggest getting an AGM type battery (Absorbed Glass Mat) these things are incredibly strong (Very Heavy) and are good for deep cycle and cranking... have an excellent recovery cycle... and are completey dry.. they can be mounted in any way if need be... They are however pretty expensive... at approx $380 upwards...electronic isolators are designed to charge the main battery first... once it has reached optimum voltage the isolator will switch charge to the AUX battery... In this setup you can run your fridge until the AUX battery is dead flat and still sart your car..the AUX battery will be fully charged within an hour or so or driving down the road... I have two AUX batteries and they are Lifeline N70 they do fit in the ARB front bracket... Cheers TOMUCH

http://www.lifelinebatteries.com/

[TOMUCH]

[Rich]

Yeah, there are a lot of different opinions on the subject and people should do what they are comfortable with for their configuration. The way I see it, the method I explained can never leave you with 2 flat batteries, not ever. The way you described, it can (ie if you run the accessories off your auxillary and leave your lights on or winch from the main and flatten it) unlikely I know, but I have an Auto transmission and I need to know I always have a fully charged and isolated battery. The ARB dual battery system recommends connection this way, and the relay can handle 100 Amps through it.
All comes down to individual choice really.
Cheers mate,
Rich.

Plus if you kill your main battery in the first year, toyota should replace it for free

[Doinit]

Yes Dr Jan Itor,

I went the Trojan 27TMH 12v115AH battery with the Redarc Smart Battery Isolator 12V. Plus I had the rocker switch installed in one of the 3 spare switch places under the ashtray, to use both batteries together if required.

Cheers
Doinit

[TOMUCH]

Rich, yep no problem... but considering winching amps CAN reach upwards of 400amps... I don't think your relay will last long. Also, if you run your fridge and all accessories from your cranking battery, you have a much higher chance of draining it considering cranking batteries are pretty S#$T for running AUX equipment... I would also check with ARB on how they connect their dual batteries... just sounds wrong to me..will have greater chance of flat main batttery continually relying on the AUX battery to help it out.... Cheers TOMUCH

[Doug67]

The ARB setup has a button in the cab you press if your cranking battery goes flat which connects the two battery's togeather so you can still start your 4by

[Rich]

I musn't of made myself very clear. Aux batt does not help out the main Battery when winching. 400 amps wont flow through the relay cause soon as you winch, the voltage will drop and thus isolate the batteries.

(You winch from the main battery and the Aux is isolated). No current flowing through the relay.

The method I explained is the one ARB recommend (at least in TVL). I had long conversations with them about it.

But as I said, each to their own. I don't think there is one way that suits everyone.
I am not trying or meaning to be disrespectfull in any way, but I have also discussed this with the guys at work and they had many other reasons for doing it the way I have, I just can't remember all the reasons at the moment...must be old age

Rich.

[TOMUCH]

Sorry DR Jan Itor, In answer to your actual question I use...

The GPL-31T RV / Recreational Vehicle Battery From Lifeline Battery Corporation

[url]http://www.lifelinebatteries.com/rvflyer.php?id=3[/url]

No probs Rich... I didn't mean to come off rude... I apoligise if you got that impression... Cheers TOMUCH

[Rich]

Not at all mate.
All is good.
Cheers.

Rich.